如果我使用echo，三元运算符不起作用

Question

我正在使用此三元运算符：

$this->checkIfProductCategoriesContainsString($productId, $categoryNeedle) !== false ? echo "Category containing categoryNeedle exists" : echo "Category does not exist.";

我也这样尝试过：

($this->checkIfProductCategoriesContainsString($productId, $categoryNeedle) !== false) ? echo "Category containing categoryNeedle exists" : echo "Category does not exist.";

但是我的IDE提示unexpected echo after ?

Answer 1

那

echo(
    $this->checkIfProductCategoriesContainsString($productId, $categoryNeedle) !== false
        ? "Category containing categoryNeedle exists"
        : "Category does not exist."
);

Answer 2

一般而言，您应该在print和echo之间阅读有关the difference的内容。 Tl; dr改用print。

$this->checkIfProductCategoriesContainsString($productId, $categoryNeedle) ?
    print "Category containing category needle exists" : 
    print "Category does not exist.";

但最好只是：

echo $this->checkIfProductCategoriesContainsString($productId, $categoryNeedle) ?
    'Category containing category needle exists' : 
    'Category does not exist.';